A Compiler Framework for Recovery Code Generation in General Speculative Optimizations

Abstract

Data speculation is an effective way to overcome imprecise alias analysis for many compiler optimizations. A general framework that integrates both control and data speculation using alias profiling and/or compiler heuristic rules has shown to improve SPEC2000 performance on Itanium systems [16]. However, speculative optimizations require check instructions and recovery code to ensure correct execution when speculation fails. How to generate check instructions and their associated recovery code efficiently and effectively is an issue yet to be well studied. Also, it is very important to avoid inhibiting later optimizations after the recovery code is generated in the earlier phases. This paper proposes a framework that uses an if-block structure to facilitate check instructions and recovery code generation for general speculative optimizations. It allows speculative and recovery code generated early in the compiler phases to be integrated effectively with the subsequent compiler optimization phases. It also allows multi-level speculation for multi-level pointers and multi-level expression trees to be handled with no additional complexity. The proposed recovery code generation framework has been implemented on the Open Research Compiler (ORC).